Members of a recent image sensor module have been made of various materials such as glass, metal, and liquid crystal polymer (hereinafter referred to as “LCP”). When these members made of various materials are adherends, an adhesive exhibiting high moisture resistance reliability relating to bonding strength has been demanded regardless of the materials of the adherends. It has been known that an epoxy-resin-thiol-curing-agent-based resin composition is effective for realizing recently-demanded high low-temperature fast curability (e.g., Patent Literature 1). However, there is a problem that a typical thiol-based curing agent (e.g., pentaerythritol tetrakis(3-mercaptopropionate) (Product Name: PEMP) manufactured by SC Organic Chemical Co., Ltd., trimethylolpropane tris(3-mercaptopropionate) (Product Name: TMMP) manufactured by SC Organic Chemical Co., Ltd., and pentaerythritol tetrakis(3-mercaptobutyrate) (Product Name: Karenz MT PE1) manufactured by Showa Denko K. K.) exhibits poor moisture resistance of the resin composition after curing. This might be because any of the typical thiol-based curing agents contains an ester structure in a skeleton.